Numerous ordered complex biological structures, such as collagen fiber, spider web and virus, are formed from small and relatively simple building blocks by spontaneously self-assembly. Viruses are self-assembled by capsid proteins enclosing the viral genome, and provide the most efficient transfection machinery. Inspired by nature, we designed a short peptide to resume the function of a viral capsid protein. Upon co-assembly with plasmid DNA, cocoon-like structural mimics of viruses with ordered striped capsid surface were formed. The nanostructure is morphologically similar to parapox virus. The robust peptide capsid, stabilized by β-sheets, was resistant to enzymatic digestion, thus imitating the viral capsid on the aspects of architecture as well as its gene protection function. Prompted by this discovery, we are tailoring each peptide segment to control the peptide/DNA co-assembled structure, and exploring their biological applications as gene and drug delivery vectors.